Grinding wheel dresser



Feb. 4, 1958 J. KlsH ET AL GRINDING WHEEL DRESSER 2 Sheets-Sheet l FiledFeb. 8, 1954 VEN-road C-jodep H @idk Feb. 4, 1958 Filed Feb. 8, 1954 J.KlsH ET AL GRINDING WHEEL DRESSER 2 Sheets-Sheet 2 mv @ou sph. @iufm (jprami )gv-anca@ United States Patent-O 4 Claims. (Cl. 12S-11) Thepresent invention relates to a multiple disc grindmg wheel dresser. Itnds particular although not necessarlly exclusive utility in dressing aplurality of grind- 'ing wheels which have been mounted on a grindinghead spaced for use with a particular workpiece.

Quite often, in the manufacture of transmission shafts and the like, itis necessary to machine a plurality of snap ring or similar grooves onpredetermined centers wherein the location of the centers has atolerance of from threeto ve-thousandths of an inch and the width of thesnap ring grooves has a tolerance on the order of plus or minus tenone-thousandths of an inch. Commercial manufactuuring methods dictatethe formation of such grooves by grinding as opposed to other methods ofmachining. This is normally accomplished by using a plurality ofgrinding wheels on a single grinding head. It is necessary, of course,to dress such wheels to the appropriate dimensions required by theparticular job on which they are to be used. In order to insure theaccuracy of the center locations and thicknesses of replacement grindingwheels which replace the worn wheels from time to time in the course ofmanufacture, it is desirable to refer each dressing operation to aparticular standard in order to insure uniformity.

Accordingly, its is an object of the invention to provide a grindingwheel dressing arrangement capable of dressing a plurality of grindingwheels on a single grinding head to close tolerances, both as tothicknesses and as to center locations.

An associated object of the invention is to afford a grinding wheeldressing tool which is interchangeable with the workpiece to be ground,thereby achieving the advantage of dressing the grinding wheel withoutremoving the grinding wheel head from its operating position.

An additional object of the invention has for its purpose the reducingof chatter and the consequently induced inaccuracies when thin grindingwheels are dressed at high speeds.

Further objects and advantages of the invention will become apparent asthe following description proceeds, taken in connection with theaccompanying drawings, in which:

Figure l is a cutaway plan View along the longitudinal axis of agrinding wheel dressing tool in operative relation with a grinding wheelhead.

Fig. 2 is an enlarged partial section of the diamond type dressing tipsshowing their mounting within the grinding wheel dressing tool.

Fig. 3 is an enlarged plan view looking down the longitudinal axis ofthe grinding wheel dressing tool and showing the dressing tool support.

Fig. 4 is a schematic diagram showing the operative relationship betweenthe diamond type dressing tool cutting edges and their associatedgrinding wheel to be dressed.

Although a particular embodiment of the invention has been shown anddescribed in some detail herein, there is no intention to thereby limitthe invention to such devis embedded a typical industrial diamond point25.

u2,821,974 Patented Feb. 4, 1958 tails of the embodiment. On thecontrary, the intention is to cover all modifications, alternativeembodiments, usages and equivalents of the grinding wheel dressing toolfalling within the spirit and scope of the invention as expressed in theappended claims.

In the present instance, the invention has been shown as Vembodied in agrinding wheel dressing unit 10 such as that shown in Fig. 1. Althoughthis particular unit contemplates dressing three grinding wheels, itwill be understood that the invention is adaptable to the dressing ofany number of grinding wheels ixedly located along a common axis ofrotation. The particular unit shown has been demonstrated as capable ofdressingthree grinding wheels to a thickness of less than one-tenth ofan inch on centers spaced less than two inches apart where thetolerances run in the order from plus or minus three to tenone-thousandths of an inch.

Because grinding wheels working to these dimensions must operate at highspeeds, additional dressing operational problems are introduced. Wobbleand chatter often result from uneven or too rapid a feed. The wheels maybe dressed to a proper thickness, but due to the lack of skill of theoperator, the center tolerances may not be met. The converse may also bethe case. It is desirable to refer all of these dimensions to axedstandard.

Such a xed standard in a mechanism for practicing the inventionillustrated herein is the backbone of a dressing tool 10 in the form ofan arbor 11. The axis is in operation parallel to the axis kof rotationof the grinding wheel head 12 and its associated grinding wheel discs14. Means, not shown in the drawings here, are provided forincrementally shortening the distance between the axis of rotation ofthe grinding wheel head 12 and the axis of rotation of the grindingwheel dressing tool 10 while both units are rotating. Normally, the twounits rotate in opposite directions as illustrated diagrammatically inFig. 4. The grinding wheel head ro'- ice tates with a peripheral speedof approximately five to v seven thousand feet per minute, while thegrinding wheel dressing tool 10 rotates at approximately 150 R. P. M.

More particularly, the two principal rotating elements involved appearin their operational relationship in Fig. 1. The grinding wheel head 12is fxedly mounted to a drivingly rotated spindle -15 of the grinder 16.The grinding wheels `14 are replaceably mounted within the grindingwheel head 12 at centers corresponding with the centers of `the grooveto be ground in the workpiece. It will be understood that the grinder 16is positioned for advancement toward and from the workpiece while thespindle 15 rotates at high speed.

One of the objects of the invention is to dress the new .discs in thegrinding wheel head without removing the `the grinder or similar machineused for rotating the workpiece. The dressing tool arbor 11 is adaptedfor use in association with a driving dog 20 and engaging arm 21 fordrivingly rotating it in the same fashion as` the workpiece. Locatedalong the axis of the dressing tool arbor 11 and perpendicular theretoare the dressing bit supports 22, shown here in the form of modifieddiscs, as illustrated in detail in Fig. 3.

In greater detail, it will be seen from Fig. 3 that the dressing bitsupport 22 is in the form of a disc or wheei modified at diametricallyopposed portions to mount the dressing bits 24. The dressing bits 24 arenormally cylindrical in shape, terminating at a conical point in whichThe invention, naturally, is not limited to the type of dressing `3 bitpoint or particular configuration of the dressing bits. The form ofdressing bit shown, however, serves to illustrate the type of ,dressingbit used commercially. t

For best operation, it has been found that the dressing bits 24operatein pairs, one performingA the roughing cut and kone performingy thefinishing cut. The, roughing cut dressing bit 24 is normally spaced at aradius from the center of the dressing bit support 22 at a distanceapproximately one thirty-second of an inchl greater than that of thefinishing bit. It will be appreciated, of course, that the locations ofthe dressing bits will vary as thel direction of rotation of thedressing tool arbor and grinding wheel are varied. In the particularinstance illustrated, the grinding wheels 14 rotate counterclockwisewhen viewed from the tailstock and the dressing wheel arbor 11 alsorotates lcounterclockwise when viewed from the same location, resulting`in the head-on meeting of the dressing wheel tool bit and thegrindingwheel Vto be dressed.y

Because the grinding wheel 14, particularly in thecase of snap ringgrooves `used in other applications for which the grinding wheeldressing tool of the invention finds utility, is oftentimes of thinsection (i. e., less than onetenth of an inch), a considerable amount ofchatter is often experienced in dressing the wheel. It has been foundthat the undesirable effects of chatter can be minimized byalternatively dressing the opposed faces of the grinding wheel, allowinga period of dwell during which the rotation of the wheel dampens thewobble and chatter induced during the dressing operation. Accordingly,the dressing bit support discs 22 are positioned along the arbor 11 andbored to receive the dressing points 24 in such a manner that uponrotation of the dressing tool arbor 11, the dressing bits alternativelyengage the opposing faces 'of each grinding wheel 14. Naturally, a widevariety of locations and means for fixing the dressing bits 24 to theirassociated supports 22 may be found expedient for the particular jobsinvolved. lt is important, however, to locate the dressing bits in sucha manner that they engage their grinding wheels 14 alternatively so thatthe chatter, for example, set up in the disc 14 by one pair of dressingpoints is dampened before the opposed pair of dressing bits'engages theopposite face of the grinding wheel.

The advantages and spirit of the invention are more readily appreciatewhen the step-by-step method of dressing a plurality of grinding wheelsis followed. The operation of grinding wheel dressing unit 10,exemplifying the invention, will serve as an illustration. First, therough grinding wheels 14, as received from the stock room, are removablysecured in the grinding wheel-head 12. The grinding wheel head 12 isthen, if removed from the grinder 16. replaced on the spindle 15 of theVgrinder 16. The workpiece is removed from its location between theheadstock 18 and tailstock 19 of its associatedmachine. The grindingwheel dressing tool arbor 11 Vis next substituted for the workpiecebetween the same head 18 and tail 19 stocks as used for the workpiece.The grinding wheel dressing unit 11 is then rotated at slow speed andthe grinding wheel head 12 is rotated at its normal operating speed. Thegrinder 16 is then advanced toward the dressing unit 10 at a linearspeed commensuratewith the depth and number of cuts to be made by thevarious dressing bits 24. After the grinding wheels 14 are dressedto`size, the grinder 16 is then withdrawn from the dressing unitreplaced by the workpiece.

Because the grinding wheel dressing unit can be set and adjusted inthetool room to dress all of the grinding .wheels 14 simultaneously, andrepeatedly, a fixed Vstandard Abased upon the exact working dimensionsof the Vdressing,toofunit therebyreplaces a multitude ofskilled"dressing operations required by the machine operator when each grindingsurface must be dressed individually prior to use.

We claim as our invention:

1. A dressing tool for dressing the sides of thin rotary grinding wheelscomprising a rotatable disk and a single pair of diamonds mounted on oneside of the disk near its periphery, one of said diamonds being slightlyspaced angularly and radially outwardly from the second diamond todefine a roughing point and the second diamond extending slightlyfurther from the face of the disk than the first diamond to define afinishing point.

2. A dressing tool for dressing the facing sides of a pair of thinspaced rotary grinding wheels comprising a rotatable disk having asingle pair of diamonds mounted on one side face of the disk near theperiphery thereof and a second single pair of diamonds mounted on theother side of the disk near the periphery thereof and .dlametricallyopposite the first pair, one diamond `of each pair being slightly spacedangularly and radially outwardly, from the other diamond of each pair todefine a roughing point and the other diamond of each pair. extendingslightly further from the face of the disk to define a finishing point.

3. -In a precision grinding machine having a thin grinding wheel mountedon a rotary shaft for cutting workpiece grooves, means for dressing thegrinding wheel sides comprising a disk mounted for rotation on a shaftparallel to the grinding wheel shaft in a given direction, means forlaterally moving the dressing disk shaft relative to the grinding. wheelshaft to advance the disk periphery along successive` radial portions ofthe grinding wheel side face, and a single pair of diamonds mounted onone side of the disk near the periphery thereof, the first diamond beingslightly angularly advanced with respect to the second diamond in saidgiven direction of rotation to define a roughing point, and the seconddiamond being slightly spaced radially inward with respect to the firstdiamond and extending further laterally from the disk side to define afinishing point.

4. In a precision grinding machine having a pair of thin rotary grindingwheels mounted on a rotary shaft for-cutting grooves in rotatablymounted workpieces, means for dressing the facing sides of the grindingwheels comprising a disk mounted for rotation on a shaft parallel to thegrinding wheel shaft in a given direction, means forilaterally movingthe dressing disk shaft relative to thc grinding wheel shaft to advancethe disk periphery along successive radial portions of the facinggrinding wheel sides,,a first single pair of diamonds mounted on oneside of the disk -near the periphery thereof, a second singlepairofdiamonds mounted on the other side of the disk near the peripherythereof and diametrically opposite thefirst pair, the first diamond ofeach pair being slightly angularly advanced with respect to the seconddiamondin -said given direction of rotation to define a roughingpoint,and the second diamond of each pair ,beingslightly spaced radiallyinward with respect to the first diamond and extending further laterallyfrom the disk side to define a finishing point.

lReferences Cited in the file of this patent UNITED STATES PATENTS47,255 Drake Apr. 11, 1865 161,835 Squire Apr. 16, 1875 298,353 CrumpMay 13, 1884 438,035 Turner Oct. 7, 1890 1,902,555 Hughes Mar. 2l, 19331,919,288 Bath July 25, 1933 2,073,678 .Broughton Mar. 16, 19372,322,579 Kutscha June 22, 1943 2,345,050 .Jansen Mar. 28, 19442,347,283 Ross Apr. 25, 1944 Y2,348,089 Niekirk May 2, 1944 2,659,357Osplack Nov. 17, 1953

